| Project/Area Number | 09440186 |
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
YURIMOTO Hisayoshi Graduate School of Science and Engineering Tokyo Institute of Technology, Associate Professor, 大学院・理工学研究科, 助教授 (80191485)
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| Co-Investigator(Kenkyū-buntansha) |
HIRATA Takafumi Graduate School of Science and Engineering Tokyo Institute of Technology, Associ, 大学院・理工学研究科, 助教授 (10251612)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed(Fiscal Year 1998)
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| Budget Amount *help |
¥10,800,000 (Direct Cost : ¥10,800,000)
Fiscal Year 1998 : ¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1997 : ¥7,600,000 (Direct Cost : ¥7,600,000)
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| Keywords | Meteorite / Oxygen / Secondary ion mass spectrometry / interstellar medium / isotope microscope / solar system / isotope / 惑星系 / 珪素 / マグネシウム / 2次イオン質量分析法 |
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| Research Abstract |
Interstellar media in primitive meteorites are only clue to clarify presolar history. The difference between interstellar media and solar matters is only isotope ratio of elements. We have made in-situ measurements of isotope ratios, textures, shapes and crystal structures for individual fine particles in primitive meteorites. The goal of in this study is construction of new scenario for material evolution from interstellar media to planetary matters.
A novel micro-scale analysis for oxygen isotope ratios has been developed by secondary ion mass spectrometry. A calcium-aluminum-rich inclusion (CAI) from the Allende meteorite was analyzed and found to contain melilite crystals with extreme oxygen-isotope compositions (-5 percent oxygen-16 enrichment relative to terrestrial oxygen-16). The oxygen isotopic variation measured among the minerals (melilite, spinel, and fassaite) indicates that crystallization of the CAI started from oxygen-16-rich materials that were probably liquid droplets in the solar nebula, and oxygen isotope exchange with the surrounding oxygen-16-poor nebular gas progressed through the crystallization of the CAI.Additional oxygen isotope exchange also occurred during subsequent reheating events in the solar nebula. The 160-rich dust and 160-poor gas continued together in the solar nebula from the CAI-forming period until the chondrule-forming period.
A possible scenario for new evidence would be an active protosun with bipolar out-flow. Interstellar media near the protosun has been processed thermally and then launched into outer solar system. Therefore, composition of solar nebulae distributed heterogeneously along radial direction, The characteristics of composition and isotope ratio of each planet have been achieved in the first million years of solar system evolution.
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